Question to the Department for Transport:

To ask the Secretary of State for Transport, if he will assess the effect of the introduction of 20 miles per hour speed limits in (a) town centres and (b) residential areas on pollution.

In June 2014 the Department for Transport commissioned a comprehensive three-year research project into the effects of 20mph limits.

Effects to be assessed include the impacts of 20mph limit schemes on collision and casualty levels, changes in traffic flow and impacts on air quality and noise.

Evidence is being taken from twelve core case study schemes which cover a variety of area types from metropolitan and city centre locations to small town and residential areas. Three further case studies cover local authorities that have chosen not to implement 20mph schemes.